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PubMed2006

Genetic structure among and within peripheral and central populations of three endangered floodplain violets.

Understanding the partitioning of genetic variance in peripheral and central populations may shed more light on the effects of genetic drift and gene flow on population genetic structure and, thereby, improve attempts to conserve genetic diversity. We analysed genetic structure of peripheral and central populations of three insect-pollinated violets (Viola elatior, Viola pumila, Viola stagnina) to evaluate to what extent these patterns can be explained by gene flow and genetic drift. Amplified fragment length polymorphism was used to analyse 930 individuals of 50 populations. Consistent with theoretical predictions, peripheral populations were smaller and more isolated, differentiation was stronger, and genetic diversity and gene flow lower in peripheral populations of V. pumila and V. stagnina. In V. elatior, probably historic fragmentation effects linked to its specific habitat type were superimposed on the plant geographic (peripheral-central) patterns, resulting in lower relative importance of gene flow in central populations. Genetic variation between regions (3-6%), among (30-37%) and within populations (60-64%) was significant. Peripheral populations lacked markers that were rare and localized in central populations. Loss of widespread markers in peripheral V. stagnina populations indicated genetic erosion. Autocorrelation within populations was statistically significant up to a distance of 10-20 m. Higher average genetic similarity in peripheral populations than in central ones indicated higher local gene flow, probably owing to management practices. Peripheral populations contributed significantly to genetic variation and contained unique markers, which made them valuable for the conservation of genetic diversity.

Biodiversity↗

PubMed2005

Differential effects of interspecific interactions and water availability on survival, growth and fecundity of three congeneric grassland herbs.

Fitness of individual plants and of populations depends on the rates of survival, growth and fecundity. This study tested whether vital rates were differentially affected by biotic interactions and water availability. The effects of manipulations of above-ground competition (through clipping) and water availability (through water addition) on the vital rates of seedlings of three species (Viola elatior Fries, Viola pumila Chaix and Viola stagnina Kit.) were analysed in dry, mesic and wet grasslands. Water addition and grassland type had the largest effects on survival (accounting for 41 and 24% of total variation, respectively) across species. Height growth rate was positively affected by grassland type (19%) and water addition (12%) and varied among species (8%), while leaf accumulation rates and reproduction were affected by grassland type and clipping. The data suggested facilitative effects of the canopy on seedling survival in the dry grassland. This study presents evidence that environmental conditions and biotic interactions may have differential effects on seedling survival, growth and reproduction. The findings highlight the complex interplay between spatial and temporal environmental variation and biotic interactions in structuring plant communities.

Ecosystem↗

PubMed1999

Plant cyclotides: A unique family of cyclic and knotted proteins that defines the cyclic cystine knot structural motif.

Several macrocyclic peptides ( approximately 30 amino acids), with diverse biological activities, have been isolated from the Rubiaceae and Violaceae plant families over recent years. We have significantly expanded the range of known macrocyclic peptides with the discovery of 16 novel peptides from extracts of Viola hederaceae, Viola odorata and Oldenlandia affinis. The Viola plants had not previously been examined for these peptides and thus represent novel species in which these unusual macrocyclic peptides are produced. Further, we have determined the three-dimensional structure of one of these novel peptides, cycloviolacin O1, using (1)H NMR spectroscopy. The structure consists of a distorted triple-stranded beta-sheet and a cystine-knot arrangement of the disulfide bonds. This structure is similar to kalata B1 and circulin A, the only two macrocyclic peptides for which a structure was available, suggesting that despite the sequence variation throughout the peptides they form a family in which the overall fold is conserved. We refer to these peptides as the cyclotide family and their embedded topology as the cyclic cystine knot (CCK) motif. The unique cyclic and knotted nature of these molecules makes them a fascinating example of topologically complex proteins. Examination of the sequences reveals they can be separated into two subfamilies, one of which tends to contain a larger number of positively charged residues and has a bracelet-like circularization of the backbone. The second subfamily contains a backbone twist due to a cis-Pro peptide bond and may conceptually be regarded as a molecular Moebius strip. Here we define the structural features of the two apparent subfamilies of the CCK peptides which may be significant for the likely defense related role of these peptides within plants.

Amino Acid Motifs↗

PubMed2000

Oldenlandia affinis (R&S) DC. A plant containing uteroactive peptides used in African traditional medicine.

A review of the geographical distribution, clinical use, biological activity and phytochemistry of Oldenlandia affinis (R&S) DC. is presented. During an inventory of medicinal plants in northern Congo/Brazzaville and south-western Central African Republic in 1962, 196 different species were registered, one of which was O. affinis used for the facilitation of childbirth. A medical team working in Luluabourg (Kananga) in Congo during the troubled period in 1960, discovered also the traditional use of the same plant as an oxitocic agent during labour. The plant was collected and the uterotonic substances isolated. Cyclic peptides (called Kalata-peptides) were described, and the main peptide, B1, was subjected to pharmacological and chemical investigations. Later the three-dimensional structure of the peptide was determined. Similar cyclic peptides have been isolated also from other plants in the Rubiaceae family like Chassalia pasvifoloia and Psychotria longipes, and from Viola species: Viola tricolor L. and Viola arvensis Murray. Some of these peptides, included Kalata-peptide B1, have been shown to hold antimicrobial activity. They have recently been synthesized, and they may represent a starting point for the design of new peptide antibiotics.

Animals↗

PubMed1996

Fitting hearing aids to individual loudness-perception measures.

OBJECTIVE: The purpose of this study was to compare the prescribed gain, compression ratios, compression thresholds, and the relative predicted speech intelligibility (Speech Intelligibility Index [SII], American National Standards Institute 3.79, proposed) provided by four strategies proposed for selecting hearing aid parameters for low-threshold compression hearing instruments and by a traditional threshold-based hearing aid fitting procedure. The strategies used were Desired Sensation Level Input/Output (DSLTM[i/o]; Cornelisse, Seewald, & Jamieson, 1994), Visual Input-Output Locator Algorithm (VIOLA; Cox, 1994), FIG6 strategy (Killion, Reference Note 2), Ricketts and Bentler strategy (RAB), and a threshold-based hearing aid fitting procedure (National Acoustics Laboratories-Revised [NAL-R]; Byrne & Dillion, 1986). These new strategies have been suggested as alternatives to threshold-based strategies, which do not provide the varying amounts of target gain, as a function of input level, necessary to fit low-threshold compression hearing aids. DESIGN: The electroacoustic prescriptions and the predicted speech intelligibility were calculated across all five fitting strategies for 20 subjects. The threshold and loudness growth information used for each fitting was reported previously (Ricketts & Bentler, in press). RESULTS: Comparison across prescriptions revealed that the NAL-R strategy (due to the linear gain provided) prescribed the least gain for low-level inputs and the greatest gain for high-level inputs. Gain comparisons across fitting by loudness (FBL) strategies revealed a more shallow frequency response slope for strategies that require individual measures of loudness growth (RAB, VIOLA) in comparison with strategies that assumed average data (FIG6, DSLTM[i/o]). SII results revealed greater predicted speech intelligibility for the FIG6 and the DSLTM[i/o] compared with the NAL-R, RAB, and VIOLA. These differences were most apparent in noise backgrounds and least evident when loudness differences were minimized. CONCLUSIONS: It appears that differences in SII scores across the FBL fitting strategies are due, in part, to differences in the loudness of the output signal. It is assumed that differences in high-frequency shaping may also be a factor. These data do not appear to support the use of additional clinical time to obtain individual loudness growth measures. However, due to the fact that SII results are based on average performance, it is difficult to predict whether differences across these fitting strategies would be realized in actual measures of speech intelligibility or sound quality on an individual basis.

Correction of Hearing Impairment↗

PubMed2004

New, rare or remarkable microfungi in the Italian Alps (Carnic Alps)--part II--other microfungi.

In addition to the collection of Ascomycotina in the Carnic Alps (see New, rare or remarkable microfungi in the Italian Alps (Carnic Alps) part I ) we were able to treasure about 300 species of parasitic and saprophytic microfungi. Among them Basidiomycetes, Ascomycetes and Deuteromycets like Bostrichonema polygoni (UNGER) SCHROT. on Polygonum viviparum L., Chrysomyxa rhododendri DE BY on Picea abies (L.) KARSTEN, Coleosporium tussilaginis (PERS.) BERK. I=C. cacaliae OTTH.] on Adenostyles glabra (MILL.) DC., Dasyscyphus barbatus (KUNZE) MASSEE on Lonicera nigra L., Leptosphaeria coniothyrium (FUCKEL) SACC. on Rosa canina L., Leptotrochila brunellae (LIND) DENNIS on Prunella grandiflora (L.) SCHOLLER., Marssonina kriegeriana (BES.) MAGNUS on Salix reticulata L., Puccinia alpina FUCKEL on Viola biflora L., Puccinia maculosa (STRAUSS.) ROHLING and Erysiphe cichoracearum DC. On Prenanthes purpurea L., Septoria microsora SPENG. on Gentianella germanica (WILLD.) BORNER, Urocystis orobranches (FR.) FISCH. V. WALDH. on Orobranche gracilis SM., Urocystis violae (J. SOWERBY) A. FISCHER VON WALDHEIN on Viola biflora L. and Uromyces phyteumatum (DC.) UNG. on Phyteuma spicatum L. were dominant. All samples are located in the Herbarium ESS Mycotheca Parva, Collection G.B. Feige/N. Ale-Agha.

Altitude↗

PubMed2005

[RAPD and ISSR analyses of regenerated pea Pisum sativum L. plants].

Long-term pea callus cultures of different genotypes (mutants R-9 and W-1 and cultivar Viola) were used to regenerate plants (generation R0). The regenerants displayed changes both in qualitative and in quantitative traits. The most dramatic morphological alterations and complete sterility were observed in regenerants of the cultivar Viola. To estimate the genetic differences, regenerants were compared with the original lines with the use of RAPD (random amplified polymorphic DNA) and ISSR (inter simple sequence repeat) analyses. The extent of divergence varied among regenerants and depended mostly on the original genotype. The genetic difference from the original line was no more than 1% in W-1 regenerants, 0.7-5.3% in R-9 regenerants, and 10-15% in sterile regenerants of the cultivar Viola. The genetic variation of plants regenerated from a callus culture maintained for ten years did not exceed that of plants obtained from a culture maintained for two years.

Base Sequence↗

PubMed2002

Cyclotides: a novel type of cytotoxic agents.

Cytotoxic activities of three naturally occurring macrocyclic peptides (cyclotides) isolated from the two violets, Viola arvensis Murr. and Viola odorata L., were investigated. A nonclonogenic fluorometric microculture assay was used to examine cytotoxicity in a panel of 10 human tumor cell lines representing defined types of cytotoxic drug resistance. Additionally, primary cultures of tumor cells from patients, and for comparison normal lymphocytes, were used to quantify cytotoxic activity. All three cyclotides, varv A, varv F, and cycloviolacin 02, exhibited strong cytotoxic activities, which varied in a dose-dependent manner. Cycloviolacin 02 was the most potent in all cell lines (IC50 0.1-0.3 microM), followed by varv A (IC50 2.7-6.35 microM) and varv F (IC50 2.6-7.4 microM), respectively. Activity profiles of the cyclotides differed significantly from those of antitumor drugs in clinical use, which may indicate a new mode of action. This, together with the exceptional chemical and biological stability of cyclotides, makes them interesting in particular for their potential as pharmacological tools and possibly as leads to antitumor agents.

Amino Acid Sequence↗

PubMed2004

Long-term outcome of focal dystonia in string instrumentalists.

This study describes the clinical characteristics and long-term outcome in string instrumentalists with focal task-specific dystonia. We present the results of a follow-up telephone survey of 21 violin and viola players with focal dystonia. Eighteen musicians responded to the questionnaire. Information on long-term outcome was available on average 13.8 years after onset of symptoms. Main complaints were playing-related loss of control and involuntary movements affecting the fingering hand in 16 and the bow arm in 5 patients. In 18 patients (86%), signs of abnormal posture could be detected by watching them play their instrument. Treatment attempts included nerve decompression, physical therapy, retraining, and anticholinergic medication. In selected patients, botulinum toxin injections or splint devices were offered. Only 38% of the performing artists were able to maintain their professional careers, among them none with bow arm dystonia. Focal dystonia may affect the fingering hand or bow arm in violin and viola instrumentalists. Treatment benefit is limited and in more than half of the patients, dystonia leads to the end of their musical career.

Adult↗

PubMed2001

Demographic and random amplified polymorphic DNA analyses reveal high levels of genetic diversity in a clonal violet.

We performed demographic and molecular investigations on woodland populations of the clonal herb Viola riviniana in central Germany. We investigated the pattern of seedling recruitment, the amount of genotypic (clonal) variation and the partitioning of genetic variation among and within populations. Our demographic study was carried out in six violet populations of different ages and habitat conditions. It revealed that repeated seedling recruitment takes place in all of these populations, and that clonal propagation is accompanied by high ramet mortality. Our molecular investigations were performed on a subset of three of these six violet populations. Random amplified polymorphic DNA analyses using six primers yielded 45 scorable bands that were used to identify multilocus genotypes, i.e. putative clones. Consistent with our demographic results and independent of population age, we found a large genotypic diversity with a mean proportion of distinguishable genotypes of 0.93 and a mean Simpson's diversity index of 0.99. Using AMOVA we found a strong genetic differentiation among these violet populations with a PhiST value of 0.41. We suggest that a high selfing rate, limited gene flow due to short seed dispersal distances and drift due to founder effects are responsible for this pattern. Although Viola riviniana is a clonal plant, traits associated with sexual reproduction rather than clonality per se are moulding the pattern of genetic variation in this species.

Cluster Analysis↗

PubMed1997

CT analysis of bowed stringed instruments.

PURPOSE: To determine the utility of computed tomography (CT) for the noninvasive evaluation of bowed stringed instruments. MATERIALS AND METHODS: Thirty-seven instruments that ranged in quality from student instruments to exquisite Stradivarius violins were analyzed with CT. Accuracy of thickness measurements was determined from 24 measurements of cross-sectional pieces sawed from a student violin. Accuracy of density measurements was determined from 328 CT attenuation measurements of 16 woods used in stringed instruments. RESULTS: Substantial differences of normal structure were noted between the masterpieces crafted in Cremona, Italy, and factory-produced student instruments. Unexpected defects were detected in nine of 14 instruments older than 100 years and ranged from a few wormholes (eight instruments) to many wormholes and extensive repair (one violin). CT thickness and attenuation measurements correlated well to the line of identity with actual measurements (P < .0001). Two cellos and a viola have been constructed from CT-derived information. The viola was awarded a gold medal at a recent international competition. CONCLUSION: CT provides the modern luthier and acoustic scientist with a unique tool for characterization of normal structure, defects, and repair and for accurate measurements of wood thickness and density. CT-derived information aids in the replication of original masterpieces. CT evaluation may have an important role in the valuation, insurance, and identification of valuable stringed instruments.

Equipment Design↗

PubMed2002

Selective cytotoxicity evaluation in anticancer drug screening of fractionated plant extracts.

Chosen to reflect biodiversity in a phylogenetic sense, 100 fractionated plant extracts were screened in vitro for cytotoxicity following extraction and fractionation (polypeptide isolation). Of these 100 extracts, 30 were selected and then characterized preliminarily for antitumor potency and mode of action by testing them on two cell lines and primary cultures of human tumor cells. On the basis of cytotoxicity potency, 10 of the extracts were further characterized for anticancer activity in 10 human tumor cell lines. This final testing resulted in seven potential lead plants with superior evidence of antitumor potential: Colchicum autumnale L. (Colchicaceae), Digitalis lanata Ehrh. and Digitalis purpurea L. (Plantaginaceae), Helleborus cyclophyllus Boiss. (Ranunculaceae), Menyanthes trifoliata L. (Menyanthaceae), and Viola arvensis Murr. and Viola patrinii Ging. (Violaceae). Within a database of antitumor compounds, the activity profiles of the extracts from these seven plants were compared, by correlation analysis, with those of more than 100 other compounds, including 39 standard drugs from different classes of cytotoxic mechanisms. The activity profiles of six of these candidates were uncorrelated with those of the standard drugs, possibly indicating new pathways of drug-mediated cell death.

Antineoplastic Agents, Phytogenic↗

PubMed2001

An efficient in vitro test to determine carrot genotypes resistance to cavity spot.

As part of a carrot breeding programme, our objective was to develop a test for determining genotypes resistance against two Pythium species responsible for cavity spot. Ten different media were tested for carrot callus culture, Pythium culture and dual cultures. Carrot callus growth was greater on Murashige and Skoog medium plus 1.25 microM 2.4D plus 2.5 microM BA plus 2.5 microM NAA. Pythium violae was more sensitive to medium composition than Pythium sulcatum. When carrot callus were inoculated by Pythium violae or sulcatum on Murashige and Skoog mineral medium, callus growth of Bolero, an resistant cultivar in the field, was highly inhibited whereas Nanco, a susceptible cultivar was not. Such a medium should be used for screening genotypes resistance to Pythium. A Murashige and Skoog medium supplemented with 1.25 microM 2.4D, 2.5 microM BA and 2.5 microM NAA, where callus growth was highly reduced whatever the genotype used, should be useful for selection of cell lines tolerant to Pythium.

Coculture Techniques↗

PubMed2006

[The effect of the duration of callus culture on the accumulation of genetic alterations in regenerated pea Pisum sativum L].

Two groups of regenerant plants were obtained from different pea genotypes (lines R-9 and W1 and cultivar Viola). The first group was derived after eight months of culture and the second, from calluses cultured for a prolonged (more than ten years) time. Using random amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) methods, the regenerants and the original lines were compared with regard to genetic differences. The regenerants from both groups were shown to differ in DNA polymorphism from the original lines and from one another. The divergence of the regenerants was also different, depending largely on the original genotype. Examination of genetic differences between the first and the second group showed that the variability increased with culturing time. This was particularly evident for regenerants of the Viola cultivar, in which variability ranged from 0-5% (first group of regenerants) to 10% (second group of regenerants).

DNA, Plant↗

PubMed1997

Desipramine modulates 3H-ouabain binding in rat hypothalamus.

We have previously shown that Na+, K(+)-ATPase activity in hypothalamus is increased after administration of an acute dose of desipramine, a noradrenaline uptake inhibitor (Viola et al., Cell Molec Neurobiol 9:263-271, 1989). In this report the same treatment (10 mg per kg) was applied to evaluate 3H-ouabain binding in rat brain sections by quantitative autoradiography. Results disclosed an increase in the number of ouabain binding sites in hypothalamus but not in cerebral cortex. Concomitantly, such acute DMI treatment enhanced K(+)-stimulated-p-nitrophenylphosphatase activity in hypothalamus membranes whereas it failed to modify cerebral cortex membranes. A direct interaction of DMI with the enzyme was ruled out since in vitro DMI is known to inhibit the enzyme. It may be speculated that DMI indirectly stimulates Na+, K(+)-ATPase through the increase in noradrenaline which acts in turn on the external phosphorylated site of the enzyme.

4-Nitrophenylphosphatase↗

PubMed1996

Specificity of aspartokinase III from Escherichia coli and an examination of important catalytic residues.

Aspartokinase III (AK III) has been purified from a plasmid-containing strain of Escherichia coli. The enzyme shows broad specificity for the phosphoryl acceptor substrate. Structural analogs of aspartic acid with a derivatized alpha-carboxyl group are accepted as alternative substrates by the enzyme. Derivatives at the alpha-amino group are also tolerated by AK III but with diminished catalytic activity. As has been previously observed with aspartokinase I (T. S. Angeles and R. E. Viola, 1992, Biochemistry 31, 799), derivatization of the beta-carboxyl group, which serves as the phosphoryl acceptor, does not prevent catalytic activity. These beta-derivatized analogs are capable of productive binding to these enzymes through a reversal of regiospecificity, making the alpha-carboxyl group available as the phosphoryl acceptor. Chemical modification and pH profile studies have identified the functional groups of cysteine and histidine as being involved in the catalytic activity of AK III.

Aspartate Kinase↗

PubMed1999

Recovery of catalytic activity from an inactive aggregated mutant of l-aspartase.

Two highly conserved lysyl residues have been replaced with an arginine to examine their role in the mechanism of l-aspartase from Escherichia coli. Replacement of an active-site lysine results in a significant loss of catalytic efficiency [A. S. Saribas, J. F. Schindler, and R. E. Viola (1994) J. Biol. Chem. 269, 6313-6319], while replacement of the second lysine leads to a completely inactive and insoluble protein. Fluorescence spectral evidence has suggested that the loss of activity is due to the misfolding of this aspartase mutant. Some catalytic activity is recovered when the mutant is treated with varying levels of denaturants, and extended treatment with high levels of guanidine.HCl results in the recovery of a substantial fraction of the wild-type activity from this inactive mutant. However, upon removal of the denaturant this mutant enzyme slowly reverts to its inactive and insoluble form. Treatment with an artificial chaperone system in which solubilization by detergent is followed by its removal with beta-cyclodextrin leads to a stable enzyme under nondenaturing conditions with about half the catalytic activity of the wild-type enzyme. These results confirm a structural role for lysine-55 in l-aspartase and demonstrate that additional characterization is required before conclusions can be drawn from the production of an inactive mutant.

Aspartate Ammonia-Lyase↗

PubMed2004

The invasive shrub, Lonicera maackii, reduces growth and fecundity of perennial forest herbs.

Effects of invasive plant species on native plant species are frequently assumed or inferred from comparisons, but rarely quantified experimentally. Such quantification is important to assessing risks and impacts of invasives. We quantified the effects of Lonicera maackii, an exotic shrub invasive in many eastern North American forests, on survival, growth, and reproduction of three perennial herbs: Allium burdickii, Thalictrum thalictroides , and Viola pubescens. We predicted that the spring ephemeral, A. burdickii , would be most impacted, due to early leaf expansion of L. maackii. Field experiments were carried out in two deciduous forest stands, one (Gregg's Woodlot, GW) disturbed and the other (Western Woods, WW) relatively undisturbed. In each stand, individual herbs were transplanted into a blocked design of 60 plots where L. maackii was present, absent, or removed, and monitored for 5 growing seasons. Lonicera maackii did not affect survival of transplants, but reduced growth and final size of individuals of all three species. For two of the species, A. burdickii and V. pubescens, L. maackii reduced the proportion of live plants flowering in both stands, and reduced the seed or fruit number per flowering individual in GW. For T. thalictroides the proportion flowering was not affected, but seed number per flowering plant was reduced by L. maackii in both stands. For all three species, cumulative seed production over the course of the study was reduced by L. maackii. Overall, effects on the spring ephemeral, A. burdickii, were similar to effects on the other herbs. Because mortality of these established individuals was not affected, short-term studies might conclude forest herbs are unaffected by invasive shrubs. However, the growth and reproduction impacts documented here suggest that populations are impacted in the long-term.

Allium↗